In general, vacuum valves for substantially gas-tight closing of a flow path, flow passage or beam path, which leads through an opening formed in a valve housing, are known in different embodiments from the prior art. Vacuum slide valves are used in particular in the field of IC and semiconductor manufacturing but also, for example, in the field of electron microscopy, which must also take place in a protected atmosphere, if possible without the presence of contaminating particles.
For example, in a manufacturing plant for semiconductor wafers or liquid crystal substrates, the highly sensitive semiconductor or liquid crystal elements sequentially pass through a plurality of process chambers in which the semiconductor elements located within the process chamber are processed by means of a processing device, respectively. Both during the processing process within the process chamber, as well as during transport from process chamber to process chamber, the highly sensitive semiconductor elements must always be in a protected atmosphere—especially in a vacuum. The process chambers are connected to each other via connecting passages, for example, wherein the process chambers are opened by means of vacuum slide valves for transferring the parts of the one to the next process chamber and can be closed in a gas-tight manner for performing the respective manufacturing step. As a result of the described field of application, such valves are also referred to as a vacuum transfer valves and also as rectangular slide valves due to their rectangular opening cross-section.
Peripheral valves are used in particular for controlling or regulating the gas flow between a vacuum chamber and a vacuum pump or a further vacuum chamber. Peripheral valves are located, for example, within a piping system between a process vacuum chamber or a transfer chamber and a vacuum pump, the atmosphere or another process vacuum chamber. The opening cross-section of such valves, also called pump valves, is generally smaller than in a vacuum transfer valve. Since peripheral valves are not only used for fully opening and closing an opening, but also for controlling or regulating a flow by continuously adjusting the opening cross-section between a full open position and a gas-tight closed position depending on the application, they are also referred to as control valves. One possible peripheral valve for controlling or regulating the gas flow is the pendulum valve.
In a typical pendulum valve, as known for example from U.S. Pat. No. 6,089,537 (Olmsted), in a first step, a generally round valve disk is rotationally pivoted via an opening, which is generally also round, from an opening-releasing position into an intermediate position covering the opening. In the case of a slide valve, as described for example in U.S. Pat. No. 6,416,037 (Geiser) or U.S. Pat. No. 6,056,266 (Blecha), the valve disk, as well as the opening, is usually rectangular and is pushed linearly in this first step from a position releasing the opening into an intermediate position covering the opening. In this intermediate position, the valve disk of the pendulum or slide valve is located in a spaced opposite position to the valve seat surrounding the opening. In a second step, the distance between the valve disk and the valve seat is reduced, so that the valve disk and the valve seat are pressed uniformly against each other and the opening is closed substantially gas-tight. This second movement is preferably carried out substantially in a direction perpendicular to the valve seat. The sealing can occur, for example, either via a sealing ring arranged on the closure side of the valve disk which is pressed onto the valve seat surrounding the opening, or via a sealing ring on the valve seat, against which the closure side of the valve disk is pressed. Due to the two-step closing process, the sealing ring between the valve disk and the valve seat is hardly subjected to shearing forces that would destroy the sealing ring, since the movement of the valve disk in the second step takes place substantially rectilinearly perpendicular to the valve seat.
Different drive systems are known from the prior art for achieving this combination of a rotary movement in the pendulum valve and translatory movement of the valve disk parallel over the opening and a substantially translational movement perpendicular to the opening, for example from U.S. Pat. No. 6,089,537 (Olmsted) for a pendulum valve and from U.S. Pat. No. 6,416,037 (Geiser) for a slide valve.
The pressing of the valve disk on the valve seat must be such that both the required gas tightness is ensured within the entire pressure range, as well as damage to the sealing medium, in particular the sealing ring in the form of an O-ring or other forms of seals, is avoided by excessive pressure stress. In order to ensure this, known valves provide a controlled contact pressure regulation of the valve disk depending on the pressure difference prevailing between the two valve disk sides. However, especially with large pressure fluctuations or the change from negative pressure to positive pressure, or vice versa, a uniform force distribution along the entire circumference of the sealing ring is not always guaranteed. In general, the aim is to decouple the sealing ring from supporting forces resulting from the pressure applied to the valve. In U.S. Pat. No. 6,629,682 (Duelli), a vacuum valve with a sealing medium is proposed for this purpose, which is composed of a sealing ring and an adjoining support ring, so that the sealing ring is substantially freed of supporting forces.
In order to achieve the required gas-tightness, optionally for both overpressure and negative pressure, additionally or alternatively to the second movement step, some known pendulum valves or slide valves provide a valve ring which can be displaced perpendicularly to the valve disk and surrounds the opening and which for gas-tight closure of the valve is pressed against the valve disk. Such valves with valve rings which are actively displaceable relative to the valve disk are known, for example, from DE 1 264 191 B1, DE 34 47 008 C2, U.S. Pat. No. 3,145,969 (von Zweck) and DE 77 31 993 U. U.S. Pat. No. 5,577,707 (Brida) discloses a pendulum valve having a valve housing with an opening and a valve disk which is pivotable in parallel across the opening for controlling a flow through the opening. A valve ring, which encloses the opening, is vertically movable in the direction of the valve disk by means of several springs and compressed air cylinders. A possible further development of this pendulum valve is proposed in US 2005/0067603 A1 (Lucas et al.).
From EP 2 551 564 A1 (VAT Holding AG), a vacuum valve in various embodiments is known which comprises a two-part valve disk. A first disk section, which carries a radial seal, has an opening. A second disk section is also movably disposed in a radially sealed manner relative to the first disk section. The first disk section is pressed against the valve seat by means of the actuator, so that a sealing contact is formed, wherein the second disk section—in particular in the case of an overpressure on a valve seat side—optionally rests on an opposite valve housing side.